#########################################################################
#  -*- coding:utf-8 -*-  
#  File Name: orm.py
#  Author: lcs
#  Mail: liuchengsheng95@qq.com
#  Created Time: 2017-09-14 21:25:27
#########################################################################

#/usr/bin/python

import asyncio,logging

import aiomysql

def log(sql, args=()):
    logging.info('SQL: %s' % sql)

async def crate_pool(loop, **kw):
    logging.info('create database connection pool ...')
    global __pool
    __pool = await aiomysql.create_pool(
        host = kw.get('host','localhost'),
        port = kw.get('port',3306),
        user = kw['user'],
        password = kw['password'],
        db = kw['db'],
        charset = kw.get('charset','utf-8'),
        autocommit = kw.get('autocommit', True),
        maxsize = kw.get('maxsize',10),
        minsize = kw.get('minsize',1),
        loop = loop
    )

async def close_pool():
    '异步关闭连接池'
    logging.info('close database connection pool...')
    global __pool
    __pool.close()
    await __pool.wait_close()

async def select(sql, args, size=None):
    log(sql, args)
    global __pool
    async with __pool.get() as coon:
        async with conn.cursor(aiomysql.DictCursor) as cur:
            await cur.excute(sql.replace('?', '%s'), args or ())
            if size:
                rs = await cur.fetchmany(size)
            else:
                rs = await cur.fetchall()
        logging.info('rows returnd: %s' % len(re))
        return rs

async def excute(sql, args, autocommit=True):
    log(sql)
    async with __pool.get() as conn:
        if not autocommit:
            await conn.begin()
        try:
            async with conn.cursor(aiomysql.DictCursor) as cur:
                await cur.execute(sql.replace('?', '%s'), args or ())
                affected = cur.rowcount
                if not autocommit:
                    await conn.commit()
        except BaseException as e:
            if not autocommit:
                await conn.rollback()
                raise
        return affected

def create_args_string(num):
    L = []
    for n in range(num):
        L.append('?')
    return ', '.join(L)

class Field(object):

    def __init__(self, name, column_type, primary_key, default):
        self.name = name
        self.column_type = column_type
        self.primary_key = primary_key
        self.default = default

    def __str__(self):
        return '<%s, %s: %s>' % (self.__class__.__name__, self.column_type, self.name)

class StringField(Field):
    
    def __init__(self, name=None, primary_key = False, default = None, ddl="varchar(100)"):
        super().__init__(name, ddl, primary_key, default)
    
class BooleanField(Field):

    def __init__(self, name = None, default = False):
        super().__init__(name, 'boolean', False, default)

class IntegerField(Field):

    def __init__(self, name = None, primary_key = False, default = 0):
        super().__init__(name, 'bigint', primary_key, default)

class FloatField(Field):

    def __init__(self, name = None, primary_key = False, default = 0.0):
        super().__init__(name, 'real', primary_key, default)

class TextField(Field):

    def __init__(self, name = None, default = None):
        super().__init__(name, 'text', False, default)

class ModelMetaClass(type):
    def __new__(cls, name, bases, attrs):
        if name == 'Model':
            return type.__new__(cls, name, bases, attrs)
        tableName = attrs.get('__table__', None) or name
        logging.info('Found model: %s (table: %s)' % (name, tableName))
        mappings = dict()
        fields = []
        primaryKey = None
        for k, v in attrs.items():
            if isinstance(v, Field):
                logging.info('   Found mapping: %s => %s' % (k, v))
                mappings[k] = v
                if v.primary_key:
                    # 找到主键
                    if primaryKey:
                        raise BaseException('Duplicate primary key fo field: %s' % k)
                else:
                    fields.append(k)
        if not primaryKey:
            raise BaseException('Primary key not found.')
        for k in mappings.keys():
            attrs.pop(k)
        escaped_fields = list(map(lambda f:'`%s`' %f, fields))
        attrs['__mappings__'] = mappings
        attrs['__table__'] = tableName
        attrs['__primary_key__'] = primaryKey
        attrs['__fields__'] = fields
        attrs['__select__'] = 'select `%s`, %s from %s' %(primaryKey, ', '.join(escaped_fields), tableName)
        attrs['__insert__'] = 'insert into `%s` (%s, `%s`) values(%s)' % (tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields) + 1))
        attrs['__update__'] = 'update `%s` set %s where `%s` = ?' % (tableName, ', '.join(map(lambda f: '`%s` = ?' % (mappings.get(f).name or f), fields)), primaryKey)
        attrs['__delete__'] = 'delete from `%s` where `%s` = ?' % (tableName, primaryKey)
        return type.__new__(cls, name, bases, attrs)

class Model(dict, metaclass = ModelMetaClass):
    def __init__(self, **kw):
        super(Model, self).__init__(**kw)

    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r"'Model' object has no attribe '%s'" % key)

    def __setattr__(self, key, value):
        self[key] = value

    def getValue(self, key):
        return getattr(self, key, None)

    def getValueOrDefault(self, key):
        value = getattr(self, key, None)
        if value is None:
            field = self.__mapping__[key]
            if field.default is not None:
                value = field.default() if callable(field.default) else field.default
                logging.debug("using default value for %s: %s" % (key, str(value)))
                setattr(self, key, value)
        return value

    @classmethod
    async def findAll(cls, where = None, args = None, **kw):
        ' find objects by where clause. '
        sql = [cls.__selcet__]
        if where:
            sql.append('where')
            sql.append(where)
        if args is None:
            args = []
        orderBy = kw.get('orderBy', None)
        if orderBy:
            sql.append('order by')
            sql.append(orderBy)
        limit = kw.get('limit', None)
        if limit is not None:
            sql.append('limit')
            if isinstance(limit, int):
                sql.append('?')
                sql.append(limit)
            elif isinstance(limit,tuple) and len(limit) == 2:
                sql.append('?, ?')
                sql.append(limit)
            else:
                raise ValueError('Invalid limie value: %s' % str(limit))
        rs = await select(' '.join(sql),args)
        return [cls(**r) for r in rs]

    @classmethod
    async def findNumber(cls, selectField, where = None, args = None):
        'find number by select and where'
        sql = ['select %s _num_from `%s`' % (selectField, cls.__table__)]
        if where:
            sql.append('where')
            sql.append(where)
        rs = await select(' '.join(sql), args, 1)
        return rs[0]['__num__']
    @classmethod
    async def find(cls, pk):
        'find object key by primary key'
        rs = await select('%s where `%s` = `?`' % (cls.__select__, cls.__primary_key__, [pk], 1))
        if len(rs) == 0:
            return None;
        return cls(**rs[0])
    async def save(self):
        args = list(map(self.getValueOrDefault, self.__fields__))
        args.append(self.getValueOrDefault(self.__primary_key__))
        rows = await excute(self.__insert__, args)
        if rows != 1:
            logging.warn('find to insert record: affetced rows: %s' % rows)
    async def update(self):
        args = list(map(self.getValueOrDefault, self.__fields__))
        args.append(self.getValueOrDefault(self.__primary_key__))
        rows = await excute(self.__update__, args)
        if rows != 1:
            logging.warn('find to update by primary key: affetced rows: %s' % rows)
    async def remove(self):
        args = [self.getValue(self.__primary_key__)]
        rows = await excute(self.__remove__, args)
        if rows != 1:
            logging.warn('failed to remove by primary key: affetced rows： %s' % rows)
